What Your Birth Order Says About Your Weight

It's a pretty obvious fact that your family history predetermines your body type—after all, it only makes sense that you'd share a similar build with Mom or Dad. But who knew that you could blame your siblings? A fascinating new study shows that your birth order can play a major role in your ability to lose weight—especially if you're an older sister.

After studying the medical records of 13,000 pairs of sisters over the course of 20 years, scientists in Sweden and New Zealand found that firstborn women were 29 percent more likely to be overweight, and 40 percent more likely to be obese than their younger sisters. The older sisters were also more predisposed to conditions like diabetes and high blood pressure.

Sadly, the scientists aren't quite sure why this happens. Their best guess—no joke—is good 'ol favoritism: Parents have a tendency to over-pamper their first children. Still, dietary issues seem like a pretty steep trade for a little extra coddling, no?

Youngest or oldest, we can't all be genetically #blessed with a model bod—but Elle Macpherson's Super Elixir ($135) does wonders to curb cravings and whittle your waistline.